This invention relates generally to range measuring systems and more particularly to range measuring systems wherein range is determined by measuring the time of arrival of wave energy.
As is known in the art, range measuring systems have a wide range of applications. One such system includes a transmitter for transmitting a pulse of wave energy, such as a radar or sonar pulse, directing such pulse towards an object, detecting a reflection by the object of such pulse, measuring the time of arrival of the detected reflection, and determining the range to the object from such measured time of arrival. In this case, called pulse-echo mode, the range is calculated as half the roundtrip travel time, times the speed of propagation. In other systems called transmit-receive mode, the range to the actual source of the wave energy itself is detected. One such system is described in U.S. Pat. No. 5,280,457, issued Jan. 18, 1994, and entitled Position Detection System and Method. Such U.S. Patent describes the use of a peak detector to detect the peak of the wave energy and from the detected peak, the time of arrival of the wave energy. In such system, the peak of the wave energy is determined using a differentiator circuit. Another system is described in U.S. Pat. No. 5,142,506, issued Aug. 25, 1992 and entitled Ultrasonic Position Locating Method and Apparatus Therefor.